1. Field of the Invention
The present invention relates to a pharmaceutical composition for preventing and treating inflammation and cutaneous photodamage, which contains a water-soluble extract from a plant of Solanum genus. The composition also has a photoprotective effect, and can be used as a cosmetic composition.
2. Description of the Related Art
In aerobic organisms, oxygen is utilized in aerobic respiration, thereby producing reactive oxygen species (ROS) and free radicals. Ultraviolet (UV), ionizing radiation, and certain medications or xenobiotics will also stimulate production of ROS and free radicals. ROS and free radicals are likely to react with components within the cell (e.g., DNA, protein and lipids etc.) due to instability thereof, thereby resulting in oxidative damage to cells and tissues.
In general, antioxidant enzymes in organisms form an interacting network to protect cells and tissues from oxidative damage. Oxidative stress forms when ROS and free radicals exceed the antioxidant capacity provided by the interacting network of the cells or tissues. It has been reported that oxidative stress plays an important role in the pathological process of inflammation and photodamage (Simon R. et al (2010), Free radical biology & Medicine, 49:1603-1616; Afaq F. et al. (2006), Experimentla Dematology, 15:678-684).
Inflammation is a protective response of cells or tissues to pathogen and external stressful stimuli. During inflammation, the cells or tissues at a site of injury will stimulate the expression of specific genes through NF-kB, followed by an increased expression of chemokines, thereby leading to the accumulation of polynuclear leukocytes, monocytes, macrophages and mast cells at the site of injury (i.e., infiltration). The recruited macrophages will be activated by lipopolysaccharides (LPS) that are expressed on a surface of a pathogen. The activated macrophages will induce the expression of proinflammatory genes (including cylooxygenase-2 gene, COX-2, and inducible nitric oxide synthase gene, iNOS) to reinforce inflammatory response. In addition, the activated macrophages release ROS and free radicals to kill pathogens. However, prolonged inflammatory response leads to oxidative stress and damage due to excess accumulation of ROS and free radicals, thereby resulting in chronic inflammation and ultimately potentiating the possibility of chronic illnesses or cancer.
Photodamage occurs when skin of an organism is exposed to ultraviolet (especially ultraviolet-B, UV-B), leading to skin damage. Exposure to UV radiation will accelerate the accumulation of ROS and free radicals in skin cells, increase oxidative stress to the skin cells and induce expression of matrix metalloproteinases (MMP), thereby resulting in oxidative photodamage. Symptoms of oxidative photodamage include: telangiectasia, thinning of epidermis, reduction in collagen fiber and elastic fiber, dryness, wrinkle formation, inflammatory cell infiltration, premature skin aging and skin pathologic change.
In recent years, phytochemicals or phytochemopreventive agents derived from plants have been proven to have antioxidant, anti-inflammatory properties and improve photodamage. Examples of the phytochemical include: green tea polyphenols (GTPs), epigallocatechin gallate (EGCG), genistein, resveratrol, curcumin, apigenin, lycopene, etc. (Adhami V. M. et al (2008), Photochem. Photobiol., 84:489-500). The phytochemicals have been proven to be safer for clinical application without undesired side effects, and have caught attention in the field of medical research.
Plants of Solanum genus include Solanum incanum L., synonymous with Solanum undatum, Solanum incanum Ruiz. & Pav., Solanum coagulans Forsskal; bitter apple in English), Solanum indicum, Solanum nigrum (Long kui in Chinese; black nightshade in English), Solanum capsicastrum (false jerusalem cherry in English), Solanum xanthocarpum, Solanum melongena, Solanum coagulans, Solanum tuberosum, Solanum sodomeum (apple of Sodom in Australia), Solanum turburosum, Solanum aculeastrum, Solanum lycocarpum, Solanum khasianum, Solanum suaveolens, Solanum uporo, Solanum abutiloides, Solanum coccineum, Solanum unguiculatum, Solanum robustum, Solanum anguivi, Solanum platanifolium, Solanum mammosum, etc. It is known that steroidal alkaloids can be extracted from the Solanum genus, and commonly include solasonine and solamargine.
U.S. Pat. No. 7,078,063 B2 issued to the inventors of the present invention discloses a water-soluble extract from a plant of Solanum genus, especially Solanum incanum L., which includes at least 60 wt % of solasonine and solamargine., and a method for preparing the water-soluble extract. The patent is hereby incorporated by reference in its entirety.
In the aforesaid US patent, the inventors found that the water-soluble extract can inhibit the growth of tumor/cancer cells (specifically liver tumor cells, lung cancer cells, and breast cancer cells). In this invention, the inventors unexpectedly found that the water-soluble extract effectively cure and/or prevent inflammation and cutaneous photodamage.